Constant Function and Variable

[nandosman]

Whats the difference between constant functions and constant variables?
In a code, what's better? :

- having a bunch of constant globals with the parameters of my spell

or

- having a bunch of constant functions that returns the parameters of my spell

 

[Darthfett]

Functions are generally useful for using in a formula, variables are generally useful for using as a generic value.

Both constant functions and globals will inline (functions only if they follow the inline rules as outlined in the JassHelper Manual), so there's no performance difference.

 

[nandosman]

and for code presentation, what do you recomend? (Spell Rawcodes and constants in functions or globals?)

 

[Komaqtion]

Globals
If you want to do something like "damage-to-be-dealt-at-a-certain-time", then use a constant function like this (Example ):

constant function Damage takes integer spellvl returns real
    return I2R( spellvl ) * 100
endfunction

 

[nandosman]

wouldn't that throws an error cause of I2R not being a constant function?

 

[Komaqtion]

Sure XD

Do this then

constant function Damage takes integer spellvl returns real
    return spellvl * 100.
endfunctio

 

[HellCraft]

The difference is that in constant variables, the user can change the value(say you posted your spell and someone else is using it) but not put in a formula. For example, if I type 5*level in a constant variable then there will be a compile error saying that level isn't initialized.
But in constant functions, you pass level as a parameter, so you can do 5*level. Ok, so someone else is using your spell, he wants to make the spell deal damage depending on the hero's kills. So he changes the formula to 5*level*kills instead.

Where to use what?
You can use functions when you need to get a value which depends on another value. Like damage, which depends on the level, so that you can pass level as a parameter.
You can use variables when that field will probably be constant and never change, like an animation path or the order string of the dummy spell.